CHIRACO SUMMIT  The heat of battle was tested here in California’s Mojave Desert, and now the sands of time have erased most traces of what was the world’s largest military training center.

It was 70 years ago this March that a brash major general, George S. Patton Jr., selected a broad swath of the desert for the Army’s Desert Training Center, an area that became the largest military training ground in the world. It was a dark time in the nation’s history. Japan had attacked Pearl Harbor a few months earlier and, in Europe, Hitler had taken over much of the continent and was intent on seizing North Africa.

Patton, a pilot, had crisscrossed the California desert to search for terrain to train airmen, tank units and combat troops to do battle with German tank divisions led by Nazi Gen. Erwin Rommel. He picked an area 350 miles wide and 250 miles deep that stretched into Arizona and southern Nevada. Troops quickly came to call Patton’s harsh training ground “the land that God forgot.”

Created in 1988, the General Patton Memorial Museum tells the story of the desert center. Run by a foundation, the museum is near the site of Patton’s headquarters, Camp Young. The museum was established by the family of Joe Chiraco, an Italian immigrant who operated a store and gas station here in the 1930s and who helped the general scout the desert for the new base.

“We can’t train troops to fight in the desert of North Africa by training in the swamps of Georgia,” Patton wrote. “Without training, the desert can kill faster than the enemy.”

The troops were required to run a mile in 10 minutes while carrying rifles and full packs in the desert heat. At night, they slept in tents. A daily ration of water amounted to a gallon per person, while salt tablets were staples in a diet of field rations. Patton, who could have chosen to live in the relative comfort of nearby Indio, stayed on base with the troops. While here, Patton called on experts to advise him on the desert environment. These included Roy Chapman Andrews, who explored the Gobi Desert, and Sir Hubert Wilkins, an Australian authority on tropical clothing.

The soldiers choked on sand, made worse by the clouds of dust raised by tank operations. They solved one problem by pouring diesel fuel on the ground around mess and living quarters to keep rattlesnakes, tarantulas and scorpions at bay.

Letters from the troops to loved ones help tell the story.

“A medium tank ran over one of the fellows and killed him while he was asleep,” wrote one soldier. “A person’s life is at stake every minute there. We’re training under real fire. It’s is just like being in actual battle.”